This invention relates to water repellent compositions. More particularly, this invention relates to water repellent compositions containing aqueous solutions of alkali metal organosiliconates for use on construction materials.
The use of aqueous solutions of alkali metal methyl siliconates, alkali metal ethyl siliconates, alkali metal propyl siliconates, or alkali metal phenyl siliconates in water repellent compositions for construction materials is known in the art. Reference is made, for example, to U.S. Pat. Nos. 3,955,985 and 3,956,570, both to Bosch et al.
U.S. Pat. No. 3,955,985 (sometimes referred to hereinafter as Bosch '985) discloses water repellent compositions for use on building materials, the compositions containing an aqueous solution of alkali metal alkyl and/or phenyl siliconates, an organic aqueous soluble complexing or chelating agent, and an aqueous miscible monovalent alcohol and/or ketone. Examples of the complexing or chelating agents are alkali metal salts of aminopolycarboxylic acids and polyamines such as B,B'-diaminodiethylamine and B,B',B"-triaminotriethylamine. According to Bosch '985, the compositions taught therein will impart water repellency to masonry surfaces containing free lime without having to pretreat the surface prior to application of the water repellent composition. Furthermore, according to Bosch '985, it has been impossible to form stable aqueous solutions of ethyl, propyl, or phenyl siliconates. However, the invention therein was based on the discovery that stable aqueous solutions of such siliconates could be obtained by adding to the siliconates a complexing or chelating agent and an aqueous miscible monovalent alcohol and/or ketone.
U.S. Pat. No. 3,956,570 (sometimes referred to hereinafter as Bosch '570) discloses a method for imparting water repellency to construction materials which comprises treating the construction materials with a solution containing alkali metal organosiliconates of which at least 10 percent of the alkali metal organosiliconates are alkali metal propylsiliconates. Other organo groups which may be present in the alkali metal organo-siliconates are monovalent organic groups, preferably monovalent aliphatic hydrocarbon radicals. The compositions disclosed in Bosch '570 are said to impart water repellency to masonry surfaces containing free lime and having a pH value of at least 8 without having to pretreat the surface prior to application of the water repellent composition. According to Bosch '570, it had been through that there were no differences in the effectiveness of the various hydrocarbon radicals in the alkali metal organosiliconates in regard to imparting water repellency to construction materials. However, according to the patent, it was surprisingly found that alkali metal propylsiliconates imparted substantially better water repellent properties to construction materials having a pH value of at least 8 than alkali metal methyl-, ethyl-, or vinylsiliconates.
Although stable aqueous water repellent compositions containing water-soluble siliconates are known in the art, it is continually desirable to provide alternative aqueous siliconate-containing water repellent compositions, particularly, alternative water repellent compositions which are generally stable and more aesthetically pleasing to consumers, who tend to prefer yellow translucent water repellent compositions over milky-white water repellent compositions.
It is also continually desirable to provide alternative aqueous siliconate-containing water repellent compositions which will impart water repellency to masonry surfaces containing free lime without having to pretreat the surface prior to application of the water repellent composition.
It is further desirable to provide aqueous siliconate-containing water repellent compositions which will impart water repellency to wood surfaces as well as to masonry surfaces.
The present invention is based on the discovery that translucent aqueous siliconate-containing water repellent compositions having the above characteristics can be obtained from mixtures of aminoorgano-functional alkali metal siliconates and certain alkali metal organosiliconates.